The SpamAssassin plugin

The SpamAssassin plugin provides anti-spam capabilities for Claws Mail.
SpamAssassin is a complete spam checker, featuring local tests, remote tests, Bayesian
filtering, and more. It is written in perl. This complete set of checks makes it really
good at catching spam, at the expense of filtering rather slowly.
Claws Mail also provides a Bogofilter anti-spam plugin, which does only Bayesian
filtering, making it faster than SpamAssassin.
The SpamAssassin plugin features are:

Filtering spam when mail is received, and moving it to a specific folder or
destroying it completely

Learning what is spam and what is ham, in order to better filter your mailbox

The ability to use a remote SpamAssassin server for filtering and learning

SpamAssassin can begin filtering your emails right away, as it isn't only a Bayesian
filter; but you should correct it with the learning feature if you get false positives
or false negatives.